Stop exposing imports to #loaded files

Fixes #5423

src/Compilers/CSharp/Portable/Binder/Binder.cs

@@ -270,6 +270,11 @@ internal virtual ImportChain ImportChain
             }
         }
 
+        internal virtual Imports GetImports(ConsList<Symbol> basesBeingResolved)
+        {
+            return _next.GetImports(basesBeingResolved);
+        }
+
         /// <summary>
         /// The type containing the binding context
         /// </summary>

src/Compilers/CSharp/Portable/Binder/BinderFactory.BinderFactoryVisitor.cs

@@ -801,6 +801,12 @@ internal InContainerBinder VisitCompilationUnit(CompilationUnitSyntax compilatio
                         //           + script class members and using aliases
                         //
 
+                        bool isSubmissionTree = compilation.IsSubmissionSyntaxTree(compilationUnit.SyntaxTree);
+                        if (!isSubmissionTree)
+                        {
+                            result = result.WithAdditionalFlags(BinderFlags.InLoadedSyntaxTree);
+                        }
+
                         // This is declared here so it can be captured.  It's initialized below.
                         InContainerBinder scriptClassBinder = null;
 
@@ -814,7 +820,8 @@ internal InContainerBinder VisitCompilationUnit(CompilationUnitSyntax compilatio
 
                             // NB: This binder has a full Imports object, but only the non-alias imports are
                             // ever consumed.  Aliases are actually checked in scriptClassBinder (below).
-                            result = compilation.PreviousSubmission == null
+                            // Note: #loaded trees don't consume previous submission imports.
+                            result = compilation.PreviousSubmission == null || !isSubmissionTree
                                 ? new InContainerBinder(result, basesBeingResolved => scriptClassBinder.GetImports(basesBeingResolved))
                                 : new InContainerBinder(result, basesBeingResolved =>
                                     compilation.GetPreviousSubmissionImports().Concat(scriptClassBinder.GetImports(basesBeingResolved)));

src/Compilers/CSharp/Portable/Binder/BinderFlags.cs

@@ -93,6 +93,11 @@ internal enum BinderFlags : uint
         /// </summary>
         InScriptUsing = 1 << 27,
 
+        /// <summary>
+        /// In a file that has been included in the compilation via #load.
+        /// </summary>
+        InLoadedSyntaxTree = 1 << 28,
+
         // Groups
 
         AllClearedAtExecutableCodeBoundary = InLockBody | InCatchBlock | InCatchFilter | InFinallyBlock | InTryBlockOfTryCatch | InNestedFinallyBlock,

src/Compilers/CSharp/Portable/Binder/Binder_Lookup.cs

@@ -246,7 +246,24 @@ private void LookupMembersInSubmissions(LookupResult result, TypeSymbol submissi
 
                 var isCurrentSubmission = submission == Compilation;
                 var considerUsings = !(isCurrentSubmission && this.Flags.Includes(BinderFlags.InScriptUsing));
-                var submissionImports = considerUsings ? submission.GetSubmissionImports() : Imports.Empty;
+
+                Imports submissionImports;
+                if (!considerUsings)
+                {
+                    submissionImports = Imports.Empty;
+                }
+                else if (!this.Flags.Includes(BinderFlags.InLoadedSyntaxTree))
+                {
+                    submissionImports = submission.GetSubmissionImports();
+                }
+                else if (isCurrentSubmission)
+                {
+                    submissionImports = this.GetImports(basesBeingResolved);
+                }
+                else
+                {
+                    submissionImports = Imports.Empty;
+                }
 
                 // If a viable using alias and a matching member are both defined in the submission an error is reported elsewhere.
                 // Ignore the member in such case.

src/Compilers/CSharp/Portable/Binder/BuckStopsHereBinder.cs

@@ -35,6 +35,11 @@ internal override ImportChain ImportChain
             }
         }
 
+        internal override Imports GetImports(ConsList<Symbol> basesBeingResolved)
+        {
+            return Imports.Empty;
+        }
+
         protected override SourceLocalSymbol LookupLocal(SyntaxToken nameToken)
         {
             return null;

src/Compilers/CSharp/Portable/Binder/InContainerBinder.cs

@@ -66,12 +66,7 @@ internal NamespaceOrTypeSymbol Container
             }
         }
 
-        internal Imports GetImports()
-        {
-            return GetImports(basesBeingResolved: null);
-        }
-
-        internal Imports GetImports(ConsList<Symbol> basesBeingResolved)
+        internal override Imports GetImports(ConsList<Symbol> basesBeingResolved)
         {
             Debug.Assert(_lazyImports != null || _computeImports != null, "Have neither imports nor a way to compute them.");
 
@@ -92,7 +87,7 @@ internal override ImportChain ImportChain
                     ImportChain importChain = this.Next.ImportChain;
                     if ((object)_container == null || _container.Kind == SymbolKind.Namespace)
                     {
-                        importChain = new ImportChain(GetImports(), importChain);
+                        importChain = new ImportChain(GetImports(basesBeingResolved: null), importChain);
                     }
 
                     Interlocked.CompareExchange(ref _lazyImportChain, importChain, null);
@@ -146,7 +141,7 @@ internal override bool SupportsExtensionMethods
         {
             if (searchUsingsNotNamespace)
             {
-                this.GetImports().LookupExtensionMethodsInUsings(methods, name, arity, options, originalBinder);
+                this.GetImports(basesBeingResolved: null).LookupExtensionMethodsInUsings(methods, name, arity, options, originalBinder);
             }
             else if (_container?.Kind == SymbolKind.Namespace)
             {

src/Compilers/CSharp/Portable/Compilation/CSharpCompilation.cs

@@ -1200,6 +1200,13 @@ private ImplicitNamedTypeSymbol BindScriptClass()
             return namespaceOrType as ImplicitNamedTypeSymbol;
         }
 
+        internal bool IsSubmissionSyntaxTree(SyntaxTree tree)
+        {
+            Debug.Assert(tree != null);
+            Debug.Assert(!this.IsSubmission || _syntaxAndDeclarations.ExternalSyntaxTrees.Length <= 1);
+            return this.IsSubmission && tree == _syntaxAndDeclarations.ExternalSyntaxTrees.SingleOrDefault();
+        }
+
         /// <summary>
         /// Global imports (including those from previous submissions, if there are any).
         /// </summary>
@@ -1223,7 +1230,7 @@ internal Imports GetSubmissionImports()
             }
 
             var binder = GetBinderFactory(tree).GetImportsBinder((CSharpSyntaxNode)tree.GetRoot());
-            return binder.GetImports();
+            return binder.GetImports(basesBeingResolved: null);
         }
 
         /// <summary>
@@ -1691,7 +1698,7 @@ internal Binder GetBinder(CSharpSyntaxNode syntax)
         /// </summary>
         internal Imports GetImports(SingleNamespaceDeclaration declaration)
         {
-            return GetBinderFactory(declaration.SyntaxReference.SyntaxTree).GetImportsBinder((CSharpSyntaxNode)declaration.SyntaxReference.GetSyntax()).GetImports();
+            return GetBinderFactory(declaration.SyntaxReference.SyntaxTree).GetImportsBinder((CSharpSyntaxNode)declaration.SyntaxReference.GetSyntax()).GetImports(basesBeingResolved: null);
         }
 
         private AliasSymbol CreateGlobalNamespaceAlias()

src/Compilers/CSharp/Portable/Compilation/SyntaxTreeSemanticModel.cs

@@ -1635,7 +1635,7 @@ public override ILabelSymbol GetDeclaredSymbol(SwitchLabelSyntax declarationSynt
             }
 
             InContainerBinder binder = _binderFactory.GetImportsBinder(declarationSyntax.Parent);
-            var imports = binder.GetImports();
+            var imports = binder.GetImports(basesBeingResolved: null);
             var alias = imports.UsingAliases[declarationSyntax.Alias.Name.Identifier.ValueText];
 
             if ((object)alias.Alias == null)
@@ -1666,7 +1666,7 @@ public override IAliasSymbol GetDeclaredSymbol(ExternAliasDirectiveSyntax declar
             CheckSyntaxNode(declarationSyntax);
 
             var binder = _binderFactory.GetImportsBinder(declarationSyntax.Parent);
-            var imports = binder.GetImports();
+            var imports = binder.GetImports(basesBeingResolved: null);
 
             // TODO: If this becomes a bottleneck, put the extern aliases in a dictionary, as for using aliases.
             foreach (var alias in imports.ExternAliases)

src/Compilers/CSharp/Test/Semantic/Semantics/ImportsTests.cs

@@ -106,7 +106,7 @@ public void ConcatCollidingExternAliases()
 
             var tree = comp.SyntaxTrees.Single();
             var binder = comp.GetBinderFactory(tree).GetImportsBinder((CSharpSyntaxNode)tree.GetRoot(), inUsing: false);
-            var scratchImports = binder.GetImports();
+            var scratchImports = binder.GetImports(basesBeingResolved: null);
             var scratchExternAliases = scratchImports.ExternAliases;
             Assert.Equal(2, scratchExternAliases.Length);
 
@@ -145,7 +145,7 @@ private static Imports[] GetImports(params string[] sources)
 
             var factories = trees.Select(tree => comp.GetBinderFactory(tree));
             var binders = factories.Select(factory => factory.GetImportsBinder((CSharpSyntaxNode)factory.SyntaxTree.GetRoot(), inUsing: false));
-            var imports = binders.Select(binder => binder.GetImports());
+            var imports = binders.Select(binder => binder.GetImports(basesBeingResolved: null));
             Assert.DoesNotContain(Imports.Empty, imports);
             return imports.ToArray();
         }

src/Compilers/CSharp/Test/Semantic/Semantics/InteractiveUsingTests.cs

@@ -373,17 +373,43 @@ class C { }
         }
 
         [WorkItem(5423, "https://github.com/dotnet/roslyn/issues/5423")]
-        [Fact(Skip = "https://github.com/dotnet/roslyn/issues/5423")]
+        [Fact]
         void UsingsToLoadedScript()
         {
             const string scriptSource = @"
+using System.Collections.Generic;
+using AL = System.Collections.ArrayList;
+using static System.Math;
+
+class D { }
+
 System.Type t;
 
+// Previous submission
+GetCommandLineArgs(); // using static not exposed
+t = typeof(StringBuilder); // using not exposed
+t = typeof(P); // using alias not exposed
+t = typeof(B); // declaration exposed
+
+// Current submission
 GetTempPath(); // using static not exposed
 t = typeof(File); // using not exposed
 t = typeof(F); // using alias not exposed
-
 t = typeof(C); // declaration exposed
+
+// Current file - all available
+Sin(1);
+t = typeof(List<int>);
+t = typeof(AL);
+t = typeof(D);
+";
+
+            const string previousSubmissionSource = @"
+using static System.Environment;
+using System.Text;
+using P = System.IO.Path;
+
+class B { }
 ";
 
             const string submissionSource = @"
@@ -403,18 +429,33 @@ class C { }
 
             var compilation = CreateSubmission(
                 submissionSource,
-                options: TestOptions.DebugDll.WithSourceReferenceResolver(resolver));
+                options: TestOptions.DebugDll.WithSourceReferenceResolver(resolver),
+                previous: CreateSubmission(previousSubmissionSource));
 
             compilation.VerifyDiagnostics(
-                // a.csx(4,1): error CS0103: The name 'GetTempPath' does not exist in the current context
+                // Previous submission
+
+                // a.csx(11,1): error CS0103: The name 'GetCommandLineArgs' does not exist in the current context
+                // GetCommandLineArgs(); // using static not exposed
+                Diagnostic(ErrorCode.ERR_NameNotInContext, "GetCommandLineArgs").WithArguments("GetCommandLineArgs").WithLocation(11, 1),
+                // a.csx(12,12): error CS0246: The type or namespace name 'StringBuilder' could not be found (are you missing a using directive or an assembly reference?)
+                // t = typeof(StringBuilder); // using not exposed
+                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "StringBuilder").WithArguments("StringBuilder").WithLocation(12, 12),
+                // a.csx(13,12): error CS0246: The type or namespace name 'P' could not be found (are you missing a using directive or an assembly reference?)
+                // t = typeof(P); // using alias not exposed
+                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "P").WithArguments("P").WithLocation(13, 12),
+
+                // Current submission
+
+                // a.csx(17,1): error CS0103: The name 'GetTempPath' does not exist in the current context
                 // GetTempPath(); // using static not exposed
-                Diagnostic(ErrorCode.ERR_NameNotInContext, "GetTempPath").WithArguments("GetTempPath").WithLocation(4, 1),
-                // a.csx(5,12): error CS0246: The type or namespace name 'File' could not be found (are you missing a using directive or an assembly reference?)
+                Diagnostic(ErrorCode.ERR_NameNotInContext, "GetTempPath").WithArguments("GetTempPath").WithLocation(17, 1),
+                // a.csx(18,12): error CS0246: The type or namespace name 'File' could not be found (are you missing a using directive or an assembly reference?)
                 // t = typeof(File); // using not exposed
-                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "File").WithArguments("File").WithLocation(5, 12),
-                // a.csx(6,12): error CS0246: The type or namespace name 'F' could not be found (are you missing a using directive or an assembly reference?)
+                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "File").WithArguments("File").WithLocation(18, 12),
+                // a.csx(19,12): error CS0246: The type or namespace name 'F' could not be found (are you missing a using directive or an assembly reference?)
                 // t = typeof(F); // using alias not exposed
-                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "F").WithArguments("F").WithLocation(6, 12));
+                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "F").WithArguments("F").WithLocation(19, 12));
         }
 
         [Fact]